WIRE STRAIGHTENING MACHINE AND METHOD FOR STRAIGHTENING WIRE OR TAPE MATERIAL

Description

[0001] The invention relates to a method for straightening wire or strip material by means of a dressing device with straightening rollers which act in an offset manner on opposite sides of the material passing through, some of which straightening rollers are automatically adjusted in such a way that the straightness requirements are met depending on a model which has been determined on the basis of input data of the material, wherein the position of at least one straightening roller is continuously adapted on the basis of the said data which are recorded during the passage through the dressing device and which are representative of the straightness achieved, wherein within the model there is an X-axis in the direction of passage of the material, and a Y-axis and a Z-axis which are perpendicular to one another and to the X-axis.

[0002] The invention further relates to a wire straightening machine or a device for straightening wire or strip material with a dressing device with two rows of non-driven straightening rollers arranged longitudinally offset from one another, which during operation act on a material passing between the rows in order to straighten it, wherein some straightening rollers can be adjusted to the material in an automatically controlled manner depending on a model such that the requirements for the straightness of the material emerging from the dressing device are met, wherein within the model an X-axis lies in the direction of flow of the material, and a Y- and a Z-axis are perpendicular to one another and to the X-axis.

[0003] WO 2020 / 172694, which forms the basis for the preamble of the independent claims, teaches a method and device for straightening a wire in an adjustable straightening device. For this purpose, either the temperature of the wire, the forces acting on the straightening rollers, or the deflection of the straightened free wire after leaving the straightening device are continuously measured, entered into a model, and used to adjust the position of some straightening rollers to the wire. A disadvantage is that, when measuring the wire deflection, a free wire must be present, which cannot be directly processed by automated means.

[0004] WO 2015 / 144539 A1 discloses a method in which, within a test measurement, a relationship is determined between, among other things, forces acting on leveling rollers and "leveling material properties," such as the flatness of the material being leveled. A model is then created that allows the adjustment of leveling rollers within a leveling process based on current leveling material properties, but without measuring forces. A disadvantage is that the method only takes place within the scope of a test measurement.

[0005] The invention has for its object to provide a closed control loop for an autonomous method for straightening material of unknown, variable curvature, wherein the wire end does not have to be free, wherein the straightening machine does not have to be built much longer than conventionally, and wherein no separate test measurement run has to be carried out.

[0006] This is achieved in the method mentioned above by measuring the deflection of the material after passing through the arrangement of straightening rollers in the Y and Z directions by means of three sensors arranged along the X axis of the material and entering the measured values ​​obtained into the model that controls the adjustment of the adjustable straightening rollers.

[0007] In one embodiment of the method, the wire or strip material passes through dressing devices one after the other, one dressing device having horizontally arranged straightening rollers and the other having vertically arranged straightening rollers.

[0008] In a further advantageous alternative, the material is cut to predetermined lengths behind the third sensor as seen in the direction of travel.

[0009] The position of the material is measured behind all straightening rollers in the direction of travel by measuring the deviation of the material from the travel axis (the X-axis) in the direction of travel of the straightening rollers (Y-axis) and perpendicular to these two axes (the Z-axis). Known optical measuring methods, such as laser distance sensors (so-called laser scanners) or ultrasonic sensors, can be used for this purpose. It is conceivable that the position measurement is only performed at the beginning of the process for calibration purposes, while during ongoing operation, the measurement of the forces acting on the straightening rollers is sufficient to implement the method according to the invention.

[0010] The invention further relates to a device for carrying out the method according to the invention. The invention in such a device consists in the fact that three sensors, spaced apart in the X direction, are arranged behind the dressing device for measuring the deflection of the material in the Z and Y directions, as seen in the direction of movement of the material. All measured values ​​obtained can be fed to the model that controls the adjustment of the adjustable straightening rollers.

[0011] In an alternative of the invention, a wire cutter is arranged behind the third sensor as seen in the direction of passage.

[0012] In a further embodiment, it is preferred that the wire passes through two dressing devices one after the other, one dressing device having horizontally arranged straightening rollers and the other having vertically arranged straightening rollers.

[0013] Likewise, in an alternative, it is conceivable that, viewed in the direction of passage, a second dressing device with two rows of non-driven straightening rollers arranged longitudinally offset from one another, which, during operation, act on a material passing between the rows, is arranged behind the third sensor, wherein the second dressing device acts on the material offset by 90° from the first.

[0014] The invention is explained in more detail with reference to the drawing, in which Fig. 1 a training device with a wire running through it, Fig. 2 the same training device with indicated measuring points, Fig. 3 the graphical model of a wire deflection and Fig. 4 shows a control loop as a block diagram.

[0015] The training device of the Fig. 1 , which is prior art, has two rows of horizontal straightening rollers 3, 4, 6, 10 arranged horizontally offset from one another. One row engages the wire material 1 to be straightened at the bottom and the other row engages the wire to be straightened at the top. The wire material 1 to be straightened can also be strip material (not shown); hereinafter, the term wire material refers to the wire or strip material. The straightening rollers 3, 4, 6, 10 have no rotary drive; the wire as material 1 passes through the dressing device, which is moved in the direction of arrow 2 by feed rollers (not shown). Normally, the wire passes through two dressing devices one after the other, each offset by 90° to one another, with one dressing device having horizontal straightening rollers and the other dressing device having vertical straightening rollers. The main working range of the invention covers wire diameters between approximately 4 mm and approximately 20 mm.

[0016] The first two straightening rollers 3 of the Fig. 1 The lower rows have fixed axes of rotation. The lower straightening roller 4, which adjoins the lower straightening roller, can be individually adjusted to the passing material 1 by means of an adjusting device indicated at 5. The first three straightening rollers 6 of the upper row can be adjusted together to the material 1 and, for this purpose, are mounted on a common support 7, the height of which is adjustable by means of a lever 8 and a servomotor 9. The upper straightening roller 10, which adjoins the upper straightening rollers 6, can be individually adjusted to the material by means of an adjusting device indicated at 11.

[0017] Fig. 2 It illustrates that three sensors 13, 14, 15 are installed downstream of the straightening rollers 3, 4, 6, and 10 in the straightening system. These sensors determine the position of the straightened wire in the Y-direction and in the Z-direction (not shown, as they are perpendicular to the paper plane). The three sensors 13, 14, and 15, spaced apart in the X-direction, determine the magnitude and direction of any remaining curvature. Fig. 3 shows the model, where the curvature b is related to a predetermined length l. l is a section along the X-axis that begins behind the straightening rollers of the dressage devices. It can also be located between two dressage devices offset or rotated by 90°. Ideally, all three sensors 13, 14, and 15 are located in section l.

[0018] If the wire has a curvature in the cut state (e.g. b / l > 2 mm / m after Fig. 3 ), this is already apparent when the material 1 is clamped in front of the shears 16 or other elements of the straightening machine. The curvature is not as pronounced in the clamped state as it is after a cut by the shears 16. However, one can already tell from the wire material 1 visible after the first (of possibly two) dressing devices whether or not there is a curvature. One can even determine whether the curvature is severe.

[0019] However, the relationship is nonlinear and not directly proportional, because the wire works against a clamped state and can deflect in all directions. Therefore, the prevailing opinion in the state of the art is that the curvature of a wire can only be determined with sufficient accuracy if one end of the wire is free.

[0020] Surprisingly, the behavior of the wire with curvature when clamped at both ends can be modeled. In the method used for this, the curvature of the wire material 1 in the Y and Z directions is determined from the three position measurements. The curvature b from Fig. 3 becomes a vector in three-dimensional space. This vector is input into a nonlinear model, from which a prediction of the actual curvature, which would have to be compensated by a new adjustment of the straightening rollers 3, 4, 6, 10, is calculated. Tests have led to a nonlinear model in which the difference between the actual curvature and the prediction becomes sufficiently small in the range of the mean value of the curvature of the straight wire, i.e., the prediction is accurate enough to detect a deviation from the desired straightening result.

[0021] Using the curvature prediction, Fig. 4The state estimation is achieved in the predictive control loop. The control itself is based on a model that maps the deviation in the leveling result to the required adjustments of the leveling unit.

Claims

1. A method for straightening wire or strip material by means of a straightening device having aligning rollers engaging offset on opposite sides of the material (1) passing through, of which some are automatically set in dependence on a model which has been ascertained on the basis of input data of the material (1) so that the requirements for the straightness are met, wherein the setting of at least one aligning roller is continuously adapted on the basis of the mentioned data acquired during the passage through the straightening device, which data are representative for the achieved straightness, wherein within the model an X axis lies in the passage direction of the material (1), and a Y axis and a Z axis lie perpendicular to one another and to the X axis, characterized in that the deflection of the material (1), after the passage through the arrangement of the aligning rollers (3, 4, 6, 10) in the Y direction and in the Z direction, is measured by means of three sensors (13, 14, 15) arranged spaced apart from one another along the X axis of the material (1) and the obtained measured values are input into the model controlling the setting of the settable aligning rollers (6, 4, 10).

2. The method as claimed in claim 1, characterized in that the wire or the strip material passes through two straightening devices in succession, wherein the one straightening device has horizontally arranged aligning rollers (3, 4, 6, 10) and the other has vertically arranged aligning rollers.

3. The method as claimed in claim 1 or 2, characterized in that the material (1) is cut to predetermined lengths after the third sensor (15) viewed in the passage direction.

4. A device for carrying out the method for straightening wire or strip material as claimed in any one of claims 1 to 3, having a straightening device having two rows of nondriven aligning rollers (3, 4, 6, 10) arranged longitudinally offset in relation to one another, which engage in operation on a material (1) passing between the rows in order to straighten it, wherein some aligning rollers (6, 4, 10) are settable onto the material (1) automatically controlled in dependence on a model so that the requirements for the straightness of the material exiting from the straightening device are met, wherein within the model an X axis lies in the passage direction of the material (1), and a Y axis and a Z axis lie perpendicular to one another and to the X axis, characterized in that three sensors (13, 14, 15) spaced apart from one another in the X direction for measuring the deflection of the material (1) in the X direction and in the Y direction are arranged after the straightening device viewed in the movement direction of the material, wherein all obtained measured values can be supplied to the model controlling the setting of the settable aligning rollers (6, 4, 10).

5. The device as claimed in claim 4, characterized in that a wire cutter (16) is arranged after the third sensor (15) viewed in the passage direction.

6. The device as claimed in claim 4 or 5, characterized in that the wire (1) passes through two straightening devices in succession, wherein one straightening device has horizontally arranged aligning rollers (3, 4, 6, 10) and the other has vertically arranged aligning rollers.